The present invention relates to a composite cast tool which is cast in one continuous piece and which has at least one first portion which comprises the working component of the tool and which is manufactured from steel, and one second portion which comprises the body component of the tool and which is manufactured from grey cast iron, there being at least one interconnection zone between the steel and the grey iron.
In the manufacture of tools for sheet metalworking, such as cutting, hole making, bending or other shaping operations, it has long generally been the practice to separately manufacture a tool body by casting it from grey iron. This tool body has then been provided with a number of working components, for example steel cutters.
The tool body produced by casting has often required heat treatment after the casting operation, this being followed by machining in order to realise the requisite seats, guide shafts and bolt holes etc. for securing the steel cutters, but also to make possible fixing of the tool in a machine.
In the production of the working component or components, for example the steel cutters, the point of departure has often previously been bar material, the working components being machined to the correct form, provided with apertures for fixing bolts, guide shafts and the like, thereafter, heat treatment takes, followed by machining, for example grinding.
Producing a tool in the above-outlined manner is an extremely time-consuming operation and often determines itself the time consumption which is needed for the new production of different products.
WO 03/041895 A1 discloses a composite cast tool, as well as a method of its manufacture. According to this publication, the tool is cast in a single mould, which is thus charged with both the steel melt and the grey iron melt. During the casting of these materials, an interface or interconnection zone is formed.
In the prior art technology according to the above-mentioned publication, major problems have been encountered as regards the positioning and formation of the interface or interconnection zone between the two materials. This has had a negative effect on mechanical strength in and around the interconnection zone.
Further, it has not been possible according to the prior art technology to control in an accurate manner the temperature throughout the entire interconnection zone, which has had as a consequence that major temperature variations have occurred and resultant problems in the mechanical strength of the interconnection zone.
It is desirable to design the tool intimated by way of introduction such that the interface or interconnection zone between the steel and the grey iron may be accurately positionally determined. It is also desirable to design the tool so that it may be possible to ensure good control of the temperature at the interconnection zone.
According to an aspect of the present invention, a tool is characterised in that the first portion includes at least one projection or one wall which extends towards the body component, that the second portion includes at least one projection or one wall which extends towards the working component, corresponding projections or walls on the first and second portions being united with one another at the interconnection zone, and that the interconnection zone is substantially planar.